Internal combustion engine



FIG. 1 is a front view of the internal combustion engine showing our new design;

FIG. 2 is a rear view of thereof;

FIG. 3 is a top view of thereof;

FIG. 4 is a bottom view of thereof;

FIG. 5 is a left side view of thereof;

FIG. 6 is a right side view of thereof;

FIG. 7 is a front perspective view of thereof; and,

FIG. 8 is a rear perspective view of thereof. 

The ornamental design for a internal combustion engine, as shown and described. 